1. The Field of the Invention
The present invention relates generally to the operation of devices in wireless networks. More particularly, embodiments of the invention relate to systems and methods for generating neighbor lists used by devices operating in wireless networks.
2. The Relevant Technology
The convenience and utility of wireless devices including cellular phones is undeniable. However, there are instances where a user is unsatisfied. Whenever a user is unable to access a wireless network or whenever a user experiences a dropped call, the user is inconvenienced and unsatisfied with the performance of the wireless network. As a result, providers of wireless networks often strive to ensure that a wireless device has access to their wireless network and to ensure that adverse experiences such as dropped calls do not occur.
To achieve these goals, a wireless provider typically deploys multiple towers in the wireless network in a manner that is intended to provide satisfactory coverage. The towers are hopefully arranged in a manner that ensures, regardless of where a particular device is located in the wireless network, that the particular device has access to the network without experiencing problems such as a dropped call or weak signal.
One of the key features of wireless devices is that they are mobile in nature and are therefore unlikely to remain in the same location, even during a single call. People often use their cellular devices, for example, as they travel within the network. Because of this movement, a user is often likely to move out of the range of a particular tower and the need to switch the call over to another tower therefore arises. Further the towers used during use of the devices in the network are often approached using different paths and from multiple directions.
One of the ways that a wireless provider ensures that a call can be switched from one tower to the next and therefore ensure that the call is not dropped is through the use of neighbor lists. During a call from a wireless device, the primary sector of a tower provides the wireless device with a neighbor list. The neighbor list identifies other towers or tower sectors that the wireless device may encounter during the call. As the device changes from one primary sector to a new primary sector, the neighbor list is updated or replaced by the new primary sector.
Unfortunately, one of the common problems experienced in wireless networks is related to the neighbor list. There are many factors, for example, that make it difficult to identify the tower sectors that should be included in the neighbor list of a given sector. Variable radio propagation due to contributing factors such as terrain, deployment errors, power changes, and load based changes are examples of factors that can impact the sectors that a wireless device might encounter. As a result, the actual neighbor lists do not necessarily include all of the neighbors of the primary tower sector. Further, because users are traveling in different directions and in different paths with respect to primary sectors, their respective device are typically exercising a different portion of the primary sector's neighbor list. In other words, neighbor lists describe the possible transitions from one sector to another sector. However, making a transition from one tower sector to another tower sector may depend on the path of the user, direction of travel of the user, and other factors.
As a result of these factors, neighbor list problems can be very difficult to resolve via field testing because of all the possible paths and directions of travel that exist. In other words, different paths may indicate that different parts of a neighbor list are exercised. Thus, neighbor list are used to ensure that a call can transfer from one sector to another sector in a manner that is transparent to the user and without adversely impacting use of the device.
However, there are still problems that arise in a network that are attributable to neighbor lists. One example relates to neighbors that are not included in a neighbor list. While the fact that a particular tower sector is not included on a neighbor list may seem inconsequential, it in fact can disrupt the use of a cellular device. For example, assume that there is a tower sector that is not currently on a neighbor list of a wireless device. If this tower sector becomes a strong radio source due to environmental changes or other factors, then it is likely that the cellular communication will be lost or dropped due to interference from the missing neighbor. In other words, tower sectors that are not included in a neighbor list can interfere with existing communications and cause calls to be lost. For these and other reasons, neighbor list errors can disrupt cellular service in addition to inconveniencing users. Systems and methods are therefore needed to reduce neighbor list errors as well as to more effectively identify ideal neighbor lists for the tower sectors in a wireless network.